There are many unsolved points on the secondary arc which is one of the problems of transmission power system. An analog arc simulator in which various parameters related to the secondary arc can easily change was developed in this study. And, the theoretical formula of the secondary arc current of the transmission line by single-phase reclosing, when multi-ground faults were occurred in the multi-points on the phase conductors simultaneously, was deduced.In the 1997 fiscal year, the analog arc simulator was manufactured. And also, the theoretical formula of the secondary arc current in multi-ground faults was deduced, in addition, the effects of the phase angle between the source voltage and the secondary arc current and the peak current of the secondary arc on the duration time of the secondary arc were clarified by using the theoretical formula.In the 1998 fiscal year, the effects of the phase angle between the source voltage and the secondary arc current, the peak current of the primary arc and the peak current of the secondary arc on the dulation time of the secondary arc currente were clarified by using the analog arc simulator which was constructed in the 1997 fiscal year. In addition, it was shown that characteristics of the secondary arc current-voltage was able to formulate at the peak current of the secondary arc.The analog arc simulator developed in this study can comparatively stably generate the arc. It is possible to easily change the various parameters related to the arc, and it will be very useful for the research concerned with the arc in future.